Signal transmision method

ABSTRACT

A signal transmission method applicable to prevention of modification or alteration of the playback mode information, such as copying management information or charging information. The playback mode information form a terminal  15 P is data-converted for ciphering by a playback mode information appendage circuit  14  in a header appendage circuit  13  responsive to the key information from a terminal  15 K and the resulting information comprised of the data and the playback mode information is outputted. The reproducing side effects data conversion on the ciphered playback mode information for deciphering, by a playback mode information detection circuit  26  in a header separation circuit  25,  using the key information from a terminal  27 K, for taking out the original playback mode information at a terminal  27 P.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] This invention relates to a signal transmission method, a signalrecord (recording, recordable or recorded) medium and a signalreproducing apparatus applicable to prevention of copying orunauthorized use of transmitted or recorded and/or reproduced signals,or to a charging system.

[0003] 2. Description of the Related Art

[0004] With promulgation and increased capacity of a digital recordmedium, such as an optical disc, prevention of copying and unauthorizeduse thereof is becoming crucial. That is, digital audio data or digitalvideo data can be copied or dubbed to produce a non-deterioratedduplicate, while computer data can be easily copied to produce the samedata as the original data. The result is that the copyright tends to beinfringed by unauthorized copying.

[0005] With a view to preventing unauthorized copying, a standard forrecording the information for preventing unauthorized copying on therecord medium for original data has been proposed and used.

[0006] In an unauthorized copying preventing system in a digital audiosignal recording/reproducing apparatus, termed a rotary head digitalaudio tape recorder (R-DAT), an inhibition code for inhibiting copyingof digital data or inhibiting copying of a generation exceeding apre-set number, that is for limiting the copying generation, or aso-called inhibition code of the standard of the serial copyingmanagement system (SCMS), is recorded in a main data area for digitalaudio signals recorded on a digital audio tape as a signal recordmedium. If this inhibition code is detected by the digital audio signalrecording apparatus, the digital audio signals are prohibited from beingrecorded on a new digital audio tape.

[0007] For preventing copying of, for example, digital video signals,recorded on a signal record medium, it is also proposed in JP PatentKokai Publication JP-A-6-44755 (1994) to record pre-set ID bits, that isthe inhibition code of a standard for copying generation managementsystem (CGMS), on an original digital record medium, as in the case ofthe above-mentioned system for prevention of unauthorized copying amongrecording/reproducing apparatus for R-DAT.

[0008] In the case of computer data, the file contents themselves areciphered using the ciphering key information to permit use only byauthorized registered users. This is pertinent to a system in which adigital record medium in which the information is ciphered and recordedis distributed as a form of information circulation and the useracquires the key information for the contents he or she needs on paymentof a prescribed fee for deciphering and using the computer data.

[0009] However, as shown in JP Patent Kokai Publication No. 5-173891(1993), the above-mentioned ciphering key information or inhibition codefor the signal record medium is recorded on a specified site on therecord medium proper to the system and which is accessed by the user.

[0010] On the other hand, with the playback mode information, such ascopying management information or charging information, since bitallocation or the data position on the record medium is prefixed, thereis a risk that the information be skipped in reading or altered in use.In other words, since the playback mode information, such as the copyingmanagement information or the charging information, is at a useraccessible area, it is likely to be decoded or illegally copied by auser having a malignant intention.

[0011] In addition, if the playback mode information is arrayed in afixed manner in an optional place depending on the particular cipheringtechnique, interchangeability tends to be lost. If the playback modeinformation is arrayed fixedly, the ciphering technique is also fixed,so that it becomes poor in flexibility and extendibility, whiledurability of the format itself is likely to be lowered.

[0012] This problem is raised not only when recording/reproducing ortransmitting/receiving digital signals but also when transmitting analogsignals.

SUMMARY OF THE INVENTION

[0013] It is therefore an object of the present invention to provide asignal transmission method, a signal record (recording, recordable orrecorded) medium and a signal reproducing apparatus which renders itdifficult to make unauthorized use or duplication by modification oralteration of the playback mode information such as the copyingmanagement information or the charging information.

[0014] According to the present invention, the playback mode informationappended to a signal to be transmitted or recorded is data-converted inaccordance with the ciphering key information.

[0015] The playback mode information includes at least one of thecopying management information and the charging information, and isdesirably arrayed at a position designated by the pre-set positiondesignation information.

[0016] According to the present invention, the playback mode informationis arrayed at a position designated by the pre-set position designationinformation.

[0017] The ciphered playback mode information is difficult to alterbecause its contents cannot be known in the absence of the keyinformation, thus preventing alteration and preventing unauthorizedlistening or copying. The playback mode information, arrayed at theposition designated by the key designation information, cannot be takenout with ease, thus further improving the effect in preventingunauthorized use.

[0018] If the non-ciphered playback mode information is arrayed at aposition designated by the pre-set position designation information, theplayback mode information cannot be taken out with ease, thus preventingalteration and unauthorized use of the playback mode information.

BRIEF DESCRIPTION OF THE DRAWINGS

[0019]FIG. 1 is a block diagram showing an example of an illustrativearrangement according to the present invention.

[0020]FIG. 2 illustrates an example of a sector format.

[0021]FIG. 3 illustrates an example of the playback mode information.

[0022]FIG. 4 illustrates an embodiment of a data conversion circuit forciphering.

[0023]FIG. 5 illustrates another embodiment of a data conversion circuitfor ciphering.

[0024]FIG. 6 illustrates an example of a data record medium.

[0025]FIG. 7 illustrates an example of designating the recordingposition of the playback mode information by a pointer.

[0026]FIG. 8 illustrates an example of appendage of the playback modeinformation to analog video signals.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0027] Referring to the drawings, preferred embodiments of the presentinvention will be explained in detail.

[0028]FIG. 1 shows, in a schematic block diagram, an embodiment of anarrangement according to the present invention.

[0029] In FIG. 1, digital data, such as data obtained on digitalconversion of analog audio signals or video signals, or computer data,is supplied to an input terminal 11. The input digital data is sent to asectorizing circuit 12 so as to be sectorized in terms of a pre-set datavolume, such as 2048 bytes, as a unit. The sectorized data is sent to aheader appendage circuit 13 where header data is appended at the leadingend of each sector. The playback mode information, comprised of at leastone of the copying management information and the charging information,is contained in the header data, as later explained. The originalplayback information is also supplied to a terminal 15P of a playbackinformation appendage circuit 14. The playback information appendagecircuit 14 data-converts the original playback information forciphering, responsive to the key information from a terminal 15P, forappendage of the converted playback mode information. Output data of theheader appendage circuit 13 is sent to an error correction codingcircuit 16 where parity is appended by data delay and paritycalculations. Output data of the error correction coding circuit 16 issupplied to a modulation circuit 17 where 8-bit data, for example, isconverted in accordance with a pre-set modulation system into 16channel-bit modulated data which is sent to a synchronization appendagecircuit 18. The synchronization appendage circuit 18 appendssynchronization signals of the out-of-rule pattern, violating themodulation rule of the pre-set modulation system, in terms of a pre-setdata volume as a unit, and outputs the resulting data. And the outputsignal from the syncronization appendage circuit 18 is sent to, forexample, a recording head 19 so as to be recorded on a data record(recording, recordable or recorded) medium 20, such as a disc-shaped ortape-shaped record medium, or a semiconductor record medium, ortransmitted over a communication medium. The reproduced signal which isreproduced from the record medium by a playback head 21, or the receivedsignal which is received via a communication medium, playback inputterminal 21. The signal supplied to the input is the same signal as thatoutputted at the output terminal 19, if signal deterioration by recordor transmission is disregarded.

[0030] The signal from the playback head 21 or the communication mediumis sent to a synchronization detection circuit 22 for separation of thesynchronization signal appended by the synchronization appendage circuit18. The digital signal from the synchronization detection circuit 22 issent to a demodulation circuit 23 for demodulating the modulated signalby the modulation circuit 17. Specifically, the demodulation is suchprocessing of converting the 16 channel-bit data into 8-bit data. Thedigital data from the demodulation circuit 23 is set to an errorcorrection decoding circuit 24 where decoding as a reverse operation ofencoding by the error correction encoding circuit 16 is executed. Thedata from the error correction decoding is sent to a header separationcircuit 25 where the header in the leading portion of each sector isseparated. The playback information in the header data has beenconverted by ciphering using the key information as describedpreviously. Thus the playback mode information is converted bydeciphering by the playback mode information detection circuit 26 usingthe key information from a terminal 27K so that the decoded playbackmode information is taken out at the terminal 27P. The data freed of theheader by the header separation circuit 25, that is the so-called userdata, is sent to a sector resolution circuit 28 where the user data isresolved into sectors, each having the pres-set data volume unit, so asto be taken out at an output terminal 29.

[0031]FIG. 2 shows an illustrative example of a sector format, eachsector having, for a 2048-byte user data area 41, a 4-bytesynchronization area 42, a 16-byte header area 43 and a 4-byte errordetection code (EDC) area 44. The error correction code of the errordetection code area 44 is comprised of a CRC code of 32 bits (4 bytes)generated for the user area 41 and the header area 43. In the headerarea 43, there are a CRC (cyclic redundancy code) area 45, the playbackmode information area 46, a layer specifying one of the layers of amulti-layered disc, an address area 48 and a spare area 49.

[0032] The playback mode information 46 is comprised of a one-byte(eight bits) and configured as shown in FIG. 3, in which the 8-bitplayback mode information is made up of upper four bits of the charginginformation 51 and lower four bits of the copying management information52. The charging information 51 may be exemplified by codes or flagsspecifying whether the file or the program including the file ischarge-free or charged for viewing by a pay-per-view system or copyingby a pay-per-copy system. The 4-bit copy management information 52 isfurther divided into a two-bit copying generation data 53 and two-bitcopy permit/inhibit data 54. The two-bit copying generation data 53specifies the original, first copying generation, second copyinggeneration and third or higher copying generation by “00”, “01”, “10”and “11”, respectively. The two-bit copy permit/inhibit data 54specifies copy free, copy permitted up to the second generation, copypermitted only for the first generation and copy not permitted by “00”,“01”, “10” and “11”, respectively.

[0033] In transmitting data, for recording or transmission, for example,the original playback mode information, comprised of the charginginformation or the copy management information 52, is not directly used,but ciphered in accordance with the pre-set key information. Thisciphered playback mode information is arrayed at a pre-set position inthe sector header area 43, that is at the position of the playback modeinformation 46.

[0034]FIG. 4 shows an illustrative example of converting the 8-bitplayback mode information by way of data conversion for ciphering usingthe 8-bit key information. That is, in FIG. 4, the original playbackmode information is supplied to an input terminal 61, while the 8-bitkey information is supplied to an input terminal 62. These bit data issent to an EXOR circuit 63 so as to be Ex-ORed on the bit basis to formthe 8-bit ciphered playback mode information which is taken out at anoutput terminal 64. As the key information, for example, aidentification information is used as mentioned later.

[0035] If the ciphering is performed in this manner using the keyinformation, the contents of the original playback mode cannot be knownin the absence of the key information, such that unauthorized acts suchas modification or alteration of the contents can be preventedeffectively.

[0036]FIG. 5 shows an example in which data conversion for ciphering isperformed using not only the key information but also the 8-bit addressinformation, for example the lower one byte of the sector address. Thatis, in the example of FIG. 5, the original playback mode information,the 8-bit key information and the lower one byte (8 bits) of the sectoraddress are supplied to input terminals 65, 66 and 67, respectively.These three sorts of the 8-bit data are sent to an Ex-OR circuit 68 soas to be Ex-ORed on the bit basis to produce the 8-bit ciphered playbackmode information which is outputted at an output terminal 69.

[0037] By employing part of the sector address for data conversion forciphering, the ciphered playback mode information is varied from sectorto sector for further improving the effect in preventing alteration orunauthorized use.

[0038] Meanwhile, data conversion for ciphering is not limited to theexamples of FIGS. 4 and 5. For example, pseudo-random number of the Msequence may be used for conversion. Logic operations by AND, OR, ExOR,NAND, NOR, invertor circuits or combination circuits thereof may also beused in place of the ExOR circuit. The translocation of changing thedata positions or substitution of substituting data values may also beused for data conversion in place of the logical operations.

[0039]FIG. 6 shows a disc-shaped record medium 101, such as an opticaldisc, as an example of the record medium. The disc-shaped record medium101 has a center aperture 102 and, looking from the inner rim towardsthe outer rim thereof, a lead-in area 103, providing a programmanagement area, a program area 104 in which program data is recorded,and a lead-out area 105, providing a program end area. In the case of anoptical disc for reproducing audio or video data, audio or video data isrecorded in the program area 104, while the timing information for theaudio data or the video data is managed by the lead-in area 103.

[0040] As part of the key information, the identification informationwritten in an area other than the program area 104 as the data recordingarea may be used. Specifically, the identification information, such asproduction number proper to the record medium, the produceridentification information, distributer identification information,identification information proper to the recording device or theencoder, or the identification information proper to the device forproducing the record medium, such as a cutting machine or a stamper, maybe written in the lead-in area 103 as the TOC area or in the lead-outarea 105. That is, the identification information as the key informationis recorded in the TOC area by using the recording head 19 to which theinformation is sent. For reproduction, the identification informationmay be used as the key information for deciphering by reproducing fromthe TOC area by using the reproducing head 21. The identificationinformation may be written physically or chemically in an area inwardlyof the lead-in area 103 so as to be read out during reproduction andused as the key information for deciphering.

[0041] The playback mode information may be recorded at an optionalposition without fixing the recording position, in which case theposition designating information for designating the recording positionof the playback mode information may be written in a preset area such asa TOC area in the lead-in area 103. In such case, the recording positionfor the playback mode information may be directly designated by theposition designation information in the TOC area 103. Alternatively, thepointer in the data may be designated by the position designationinformation in the TOC area, with the recording position for theplayback mode information being then designated by the pointer.

[0042]FIG. 7 shows an example of designating the recording position forthe playback mode information by a pointer 72 as the positiondesignation information in a TOC data area 71. In FIG. 7, The pointer 72for designating the recording position for the playback mode informationis made up of sector address data 73, offset data 74, byte number data75 and attribute data. The sector address data 73, the offset data 74and the byte number data 75 designate a pre-set sector 76, an offset ofthe playback mode information in the sector 76, that is the number ofbytes from the leading position of the sector up to the playback modeinformation 77, and the number of bytes of the playback information mode77 itself, respectively.

[0043] Since the recording position for the playback mode information isnot fixed, it becomes possible to prevent the risk of extraction of theplayback mode information, such as the copying management information,from the same fixed recording position.

[0044] Although the playback mode information is modified for cipheringusing the key information or addresses as described above, the originalplayback mode information, that is the playback mode information thatexists prior to such conversion, may also be employed.

[0045] The distribution identification number, producer identificationnumber or the recording device identification number may also beemployed for the offset or the .sector address of the pointer.

[0046] The foregoing description has been made of transmission ofdigital data signals. However, the present invention may also be appliedto transmission of analog signals.

[0047]FIG. 8 shows an embodiment in which the playback mode information,in particular the copying management information, has been appended toanalog video signals.

[0048] In FIG. 8, a protect code signal 81 is mixed in a pre-sethorizontal period of a vertical blanking period of analog video signals.The horizontal period, during which the protect code 81 is arrayed, isthe 20H and 283H for an odd field and for an even field, respectively,where H denotes a horizontal period. This protect code signal 81 is madeup of, for example, 14-bit data 82 and a 6-bit error detection code(CRCC) 83. Of the 14-bit data 82, 8-bit data 85 next following a 6-bitheader 84 represents the playback mode information, in particular thecopying management information, which has been ciphered using the keyinformation, as explained previously.

[0049] As an illustrative example of the contents of the data 85specifying the 8-bit playback mode information, the most significant bit(MSB) 86 denotes copy inhibition or copy permission by “1” or “0”,respectively, while the next following two bits denote the respectivecopying generations, that is the original, first copying generation,second copying generation and the third or higher copying generations by“00”, “01”, “10” and “11”, respectively. The lower four bits 88 of thedata 85 represent a category code of the reproducing device.

[0050] By ciphering the playback mode information for the video signals,the contents of the information cannot be known without the keyinformation, such that the contents can be prohibited from beingmodified.

[0051] The present invention is not limited to the illustrativeembodiments described above. For example, the present invention can beapplied not only to recording/reproduction on or from a record mediumbut also to transmission of digital or analog signals in general. Theplayback mode information may also be modified with respect to thenumber of bits or contents or modified so as to contain the sourcecontents or copying hysteresis.

1. A signal transmission method in which the playback mode informationis appended to input signals and the resulting signal is transmitted,comprising: effecting data conversion of said playback mode informationin accordance with the ciphering key information.
 2. The signaltransmission method as claimed in claim 1 wherein said playback modeinformation includes at least one of the copying management informationand the charging information.
 3. The signal transmission method asclaimed in claim 1 wherein said conversion is performed by logicaloperations of the data of the playback mode information and theciphering key information.
 4. The signal transmission method as claimedin claim 1 wherein said key information for ciphering contains theaddress information in at least a portion thereof.
 5. The signaltransmission method as claimed in claim 1 wherein said playback modeinformation is arrayed at a position designated by the pre-set positiondesignation information.
 6. The signal transmission method as claimed inclaim 1 wherein said playback mode information is arrayed at a positioncorresponding to the vertical blanking period of the video signal.
 7. Asignal transmission method in which the playback mode information isappended to input signals and the resulting signal is transmitted,comprising: arraying said playback mode information at a positiondesignated by pre-set position designation information.
 8. The signaltransmission method as claimed in claim 7 wherein said playback modeinformation includes at least one of the copying management informationand the charging information.
 9. A signal record medium having recordedthereon a signal obtained by effecting data conversion of the playbackmode information appended to input signals in accordance with theciphering key information.
 10. The signal transmission method as claimedin claim 9 wherein said playback mode information includes at least oneof the copying management information and the charging information. 11.The signal transmission method as claimed in claim 9 wherein saidplayback mode information is arrayed at a position designated by thepre-set position designation information.
 12. The signal transmissionmethod as claimed in claim 9 wherein said playback mode information isarrayed at a position corresponding to the vertical blanking period ofthe video signal.
 13. A signal record medium having recorded thereoninput signals and the playback mode information appended thereto, saidplayback mode information being arrayed at a position designated by thepre-set position designating information.
 14. A signal reproducingapparatus for reproducing a signal obtained by data conversion of theplayback mode information appended to input signals in accordance withthe ciphering key information, comprising: key information entry meansfor entering the key information for ciphering; and means for effectingdata conversion for deciphering responsive to the key information fromsaid key information entry means.
 15. The signal reproducing apparatusas claimed in claim 14 wherein said playback mode information includesat least one of the copying management information and the charginginformation.
 16. The signal reproducing apparatus as claimed in claim 14wherein said playback mode information is arrayed at a positiondesignated by the pre-set position designation information.
 17. Thesignal reproducing apparatus as claimed in claim 14 wherein saidplayback mode information is arrayed at a position corresponding to thevertical blanking period of the video signal.
 18. A signal reproducingapparatus for reproducing input signals and the playback modeinformation appended thereto, said playback mode information beingarrayed at a position designated by the pre-set position designatinginformation, comprising: means for taking out the playback modeinformation at a position designated by said position designationinformation.